Skip to content
SetbackIQ

Retaining walls in Fairfax County, VA

A retaining wall holding back less than 3 ft of soil needs no building permit. Taller walls or walls with a surcharge do. Fairfax counts walls toward fence height limits, and marine clay or grading over 2,500 sq ft add engineering and plan review.

A person last checked these rules on October 20, 2026. This is guidance only, so confirm with Fairfax County before you build.

The details

  • Building permit when the wall supports 3 ft or more of unbalanced fill, or a driveway, structure or slope above it.High confidence
  • Walls follow fence heights: 4 ft in a front yard, 7 ft in side and rear yards.High confidence
  • On mapped marine clay, new walls and grading need a geotechnical soil report, and backfill must be at least half sand and gravel, never clay.High confidence

Check a project at your address

SetbackIQ reads the zoning, flood zone, historic district, and environmental maps for your lot. Then it applies these rules.

What are you building?

Open the checker

Common questions

When does a retaining wall need a permit or an engineer in Fairfax County?
A retaining wall holding back less than 3 ft of soil needs no building permit. Taller walls or walls with a surcharge do. Fairfax counts walls toward fence height limits, and marine clay or grading over 2,500 sq ft add engineering and plan review.

Sources

  1. Virginia USBC, 13VAC5-63-80 Section 108.2, Exemptions from application for permit. Checked 2026-10-23
    2. One story detached structures used as tool and storage sheds, playhouses, or similar uses, provided the building area does not exceed 256 square feet... 5. Fences of any height unless required for pedestrian safety as provided for by Section 3306 or used…
  2. Fairfax County Zoning Ordinance § 4102.7.A(6)-(7), freestanding accessory structures and fences. Checked 2026-10-20
    On a lot that is 36,000 square feet or less, accessory structures may not be located in the front yard... If the structure does not exceed eight and one-half feet in height, it may be located in any part of a side yard or rear yard... between eight and one-…
  3. Fairfax County LDS, Homeowner's Guide to Marine Clay. Checked 2026-10-21
    Under the Problem Soils Ordinance (Chapter 107), a soil report prepared by a qualified geotechnical engineer is required for new construction and grading work in marine clay areas... Footings in marine clay must be at least 4 feet deep... A building permit …

Disclaimer: This is general information, not legal or professional advice for any one property. Codes change. SetbackIQ is not a zoning determination, a permit, or a survey, and it does not replace an architect, engineer, or lawyer. Confirm with your building and zoning offices before you build, buy, or sign a contract.